A study that tracked rainfall patterns over thousands of years has found that dry periods coincided with eras of dynastic upheaval in China, revealing a historical link between climate stress and social unrest.
Last year was the hottest year on record, both globally and in China, according to one estimate. Extreme weather events wreaked havoc around the world, and natural disasters caused economic losses of $310 billion. Research published this month, based on an analysis of the rings of Kilian juniper trees on the Tibetan Plateau, offers a glimpse into how climate stress transformed society and power thousands of years ago.
“Given growing concerns about global climate change, it is important to understand changes in both historical and current hydroclimate,” the researchers wrote in a report published in the prestigious journal Nature. Changes in isotopes – forms of chemical elements with specific properties – in tree rings can be used to understand rainfall variability over time.
This enabled several researchers from the Chinese Academy of Sciences to reconstruct the climate record for the past 3,476 years. “Our hydro-climate reconstructions indicate that the rise and fall of several Chinese dynasties coincide with a significant transition to aridity, with three distinct phases of long-term rainfall decline following long wet periods,” the report said.
The first dry period, which lasted from 110 BC to 280 AD, saw the establishment of the short-lived Jin Dynasty and then its rapid decline. “Famine and cannibalism increased as the climate became drier after 14 AD, leading to widespread rebellion and ultimately the fall of the dynasty,” the report said.
According to the report, this dry period coincided with the wars of the Three Kingdoms period, and as a result, China’s population fell from 60 million to 30 million, along with widespread famine caused by drought. The second phase was between 330 and 770 AD. It includes the Tuyuhun, Sui, and Tang dynasties.
The third phase, from 950 to 1300 AD, corresponds to the Song Dynasty and its fall. “In the early stages of each dynasty, humid conditions were associated with periods of prosperity, while the gradual shift towards aridity consistently corresponded to their decline and eventual collapse,” the report said.
